Method for groundwater remediation using sustained-release persulfate tablets

Abstract

The present invention provides a method for groundwater remediation using sustained-release persulfate tablets, which is to synthesize the persulfate and cellulose with specific ratio to form a remediated tablet, and the manufacturing process is operated under the specific pressure. In the composition of the tablet, the persulfate is used as an oxidant while the cellulose is used as a coating agent. The compound of the tablet is coated with the cellulose to slow the releasing rate of the compound and improve the releasing time of the persulfate in the water.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for groundwater remediation using sustained-release persulfate tablets, and more particularly to a method using tablets made by mixing persulfate and cellulose under a predetermined pressure.BACKGROUND OF THE INVENTION[0002]Nowadays, the groundwater pollution occurred by gasoline and other petroleum hydrocarbons is a common and serious problem. The main source of pollution includes leaking underground storage tanks, industrial wastes or accidental spills. Since the pipelines of the gas stations and the large oil storage tanks are equipped underground, the oil is more likely to leak from pipelines because of earthquake, poor construction or other human factors. The United States has more than 2,000,000 oil storage tanks, and according to statistics, over 35% of the oil storage tanks have leaking problem. Cases of domestic oil pollution are increasing currently. The problems of soil and groundwater pollution have al...

AI Technical Summary

Benefits of technology

[0009]The present invention provides a method for groundwater remediation using sustained-release persulfate tablets, which is to synthesize the persulfate and cellulose with specific ratio to form a remediated tablet, and the manufacturing process is operated under a specific pressure. In the composition of the tablet, the persulfate is used as an oxidant while the cellulose is used as a coating agent. The compound of the tablet is coated with the cellulose to slow the releasing rate of the compound and improve the releasing time of the persulfate in the water. The persulfate, which is a sustained-release oxidant, is not easy to react with organic materials in the soil, so the required dose of persulfate in the remediated process is less than other oxidants. Therefore, the use of persulfate is not only can remove the pollutants, but also can lower the cost of remediation. By applying the stable persulfate in the persulfate chemical oxidation technology or in situ passive treatment wall, the present invention creates an integrated and oxidative remediation system for oil-polluted groundwater. Moreover, the cellulose expanded in the water because of its specific viscosity can lower the contact areas between the water and the coated compound, so that the compound is less easily dissolved in the water. By packing the sustained-release oxidant tablets composed by the persulfate and the cellulose on the treatment wall, the tablets can preserve sustained-release efficiency in polluted water. Also, since the cellulose can self-discompose in the water, the tablets can save the effort on the subsequent waste disposal process.

[0010]Comparing with conventional persulfate tablet for groundwater remediation, the present invention is advantageous because: (i) both the releasing time of oxidant in reaction region and the remediation ability are improved; (ii) the self-decomposed cellulose can prevent the groundwater from secondary contamination; (iii) the persulfate can be sustained under the earth surface for a long time; (iv) the proportions of the oxidant and cellulose can be adjusted depending on the need of polluted medium; and (v) the remediation system in present invention includes the functions of oxidation and activation, which can efficiently remove the pollutants and control the releasing time of the persulfate.

Problems solved by technology

The persulfate, which is a sustained-release oxidant, is not easy to react with organic materials in the soil, so the required dose of persulfate in the remediated process is less than other oxidants.

Moreover, the cellulose expanded in the water because of its specific viscosity can lower the contact areas between the water and the coated compound, so that the compound is less easily dissolved in the water.

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